ABCs and Cornerstone

ABCs noun - The elementary stages of any subject (usually plural).

Cornerstone and ABCs are semantically related. in basis topic. In some cases you can use "Cornerstone" instead a noun "ABCs", when it comes to topics like basic.

Cornerstone noun - An immaterial thing upon which something else rests.

ABCs and cornerstone are semantically related. Sometimes you can use "ABCs" instead a noun "Cornerstone".